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copied!<p>When you want a square or 2d grid, do something similar to what the compiler does for multidimensional arrays (real ones, not an array of pointers to arrays) and store a single large array which you index correctly.</p> <p>Example using the Matrix class below:</p> <pre><code>struct Map { private: Matrix<MapCell> cells; public: void loadMap() { Matrix<MapCell> cells (WIDTH, HEIGHT); for (int i = 0; i < WIDTH; i++) { for (int j = 0; j < HEIGHT; j++) { // modify cells[i][j] } } swap(this->cells, cells); // if there's any problem loading, don't modify this->cells // Matrix swap guarantees no-throw (because vector swap does) // which is a common and important aspect of swaps } }; </code></pre> <p>Variants of matrix classes abound, and there are many ways to tailor for specific use. Here's an example in less than 100 lines that gets you 80% or more of what you need:</p> <pre><code>#include <algorithm> #include <memory> #include <vector> template<class T, class A=std::allocator<T> > struct Matrix { typedef T value_type; typedef std::vector<value_type, A> Container; Matrix() : _b(0) {} Matrix(int a, int b, value_type const& initial=value_type()) : _b(0) { resize(a, b, initial); } Matrix(Matrix const& other) : _data(other._data), _b(other._b) {} Matrix& operator=(Matrix copy) { swap(*this, copy); return *this; } bool empty() const { return _data.empty(); } void clear() { _data.clear(); _b = 0; } int dim_a() const { return _b ? _data.size() / _b : 0; } int dim_b() const { return _b; } value_type* operator[](int a) { return &_data[a * _b]; } value_type const* operator[](int a) const { return &_data[a * _b]; } void resize(int a, int b, value_type const& initial=value_type()) { if (a == 0) { b = 0; } _data.resize(a * b, initial); _b = b; } friend void swap(Matrix& a, Matrix& b) { using std::swap; swap(a._data, b._data); swap(a._b, b._b); } template<class Stream> friend Stream& operator<<(Stream& s, Matrix const& value) { s << "<Matrix at " << &value << " dimensions " << value.dim_a() << 'x' << value.dim_b(); if (!value.empty()) { bool first = true; typedef typename Container::const_iterator Iter; Iter i = value._data.begin(), end = value._data.end(); while (i != end) { s << (first ? " [[" : "], ["); first = false; s << *i; ++i; for (int b = value._b - 1; b; --b) { s << ", " << *i; ++i; } } s << "]]"; } s << '>'; return s; } private: Container _data; int _b; }; </code></pre>

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